Bug resolution is an important activity in any software maintenance project. Bug resolution for problems reported on applications already in use (or in production) has two main implications. First, a client may discover a bug in the field, whereupon it needs to be fixed urgently. Therefore, it is important to have good tool support that can help the programmer debug the program as quickly as possible, especially when the person who is debugging the code is not the programmer who originally wrote the code. Secondly, a bug can surface despite the fact that the code has been tested and has probably been running in the field for some time. That means it is likely to be an unanticipated corner case in otherwise correct code, and automated tools can focus their effort on identifying such corner cases. To date, conventional arrangements have been far from adequate in addressing these considerations.